1. Filed of Invention
The invention relates to a hand lamp especially for magnetic crack detection and using the dye penetration process.
2. Description of Related Art
Hand lamps for crack detection are known. They are used for flaw detection in optical crack detection using the dye penetration process and magnetic crack detection to reveal the concentration of fluorescent particles in cracks in a higher concentration of dye particles by their fluorescence and thus for determining cracks. As the technical background, German Patent Application DE 19639020 A1 is mentioned, in which a generic dye penetration process is explained, the use of the hand lamp in accordance with the invention in no way being limited to this application. Typical applications of hand lamps are especially the checking of poorly accessible cavities like the inside walls of pipes, surfaces which are not illuminated in incident light—in general, areas which can be poorly reached, or rapid checking of parts on site. In the past UV hand lamps were used in which a UV burner emitted the necessary UV radiation—optionally with a filter connected on the input side. These UV burners unfortunately did not have a long service life.
Furthermore, the emission spectrum dropped to longer wavelength ranges within a short time; this led to these lamps no longer performing the task of exciting fluorescence in a certain UV range to a sufficient degree. Furthermore, the known UV sources were unwieldy and had large dimensions—this was often caused by the necessity of connecting a series reactor upstream in fluorescent tubes. In addition, there was a relatively high weight; this likewise made fine motor handling difficult.
Therefore it is a hand lamp here in which in the known manner workpieces for dye penetration testing are treated with a testing agent which has dyes, with concentration of the dyes on surface flaws, and are evaluated under illumination by an illumination means such as UV lamps for fluorescent dyes, but also lasers or other lamps with the correspondingly absorbing dyes.
Therefore, in the known manner, workpieces for dye penetration testing are prepared by cleaning them, optionally pickling and drying them, spraying with a testing agent which has dyes, especially also fluorescent dyes, with concentration of the dyes on the surface flaws, especially cracks, then wiping or scraping off the excess dye-containing testing agents, treating the workpiece which has been treated in this way optionally with a developer and then viewing it under UV light after a predetermined development time and evaluating it.
Dye penetration studies and magnetic powder tests can be carried out by operators and can be evaluated by appearance—but it is also possible to automatically evaluate them by special optical processes. The applicant has already proposed dye penetration testing processes of this type, in addition to the pertinent device.
Accordingly, the object of the invention is to avoid the disadvantages of hand lamps which emit in the UV range, especially for the dye penetration process and the magnetic powder testing process.